Do you know how many kinds of hands are the hottes

Do you know how many kinds of hands industrial robots have

for industrial robots, material handling is one of the more important applications in their grasping operation. Industrial robot is a kind of general-purpose operation equipment. Whether its operation task can be successfully completed directly depends on the clamping mechanism. Therefore, the clamping mechanism at the end of the robot should be designed in combination with the actual operation task and the requirements of the working environment, which leads to the diversification of the structural forms of the clamping mechanism

Figure 1. The relationship between the elements, features and parameters of the end effector

most mechanical clamping mechanisms are double fingered claw type, which can be divided into rotary type and translational type according to the finger movement mode; The different clamping methods can be divided into internal supporting type and external clamping type; According to the structural characteristics, it can be divided into pneumatic, electric, hydraulic and their combined clamping mechanisms

I. pneumatic end clamping mechanism

the air source of pneumatic transmission is convenient to obtain, the action speed is fast, the working medium is pollution-free, at the same time, the fluidity is better than the hydraulic system, and the pressure loss is small, which is suitable for long-distance control. The following are several pneumatic manipulator devices:

1 Rotary connecting rod lever clamping mechanism

the fingers of this device (such as V-shaped fingers and arc fingers) are fixed on the clamping mechanism through bolts, which is convenient to replace, so it can significantly expand the application of the clamping mechanism

Figure 2 structure of rotary connecting rod lever clamping mechanism

2 Straight rod type double cylinder translational clamping mechanism

the finger end of this clamping mechanism is usually installed on a straight rod equipped with a finger end mounting base, When pressure gas enters "When joining the two rod cavities of the single acting double cylinder in the manufacturing industry, it will push the piston to move towards the middle gradually until the workpiece is clamped.

Figure 3 structure diagram of the straight rod double cylinder translational clamping mechanism

3. The connecting rod crossed double cylinder translational clamping mechanism

is generally composed of a single acting double cylinder and a crossed finger. After the gas enters the middle cavity of the cylinder, it will push the two pistons to move to both sides, thus driving the connecting rod to move, The cross fingertip will firmly fix the workpiece; If no air enters the middle cavity, the piston will be reset under the action of spring thrust, and the fixed workpiece will be loosened

Figure 4 structural diagram of cross type double cylinder translational clamping mechanism

4 Internal supporting connecting rod lever clamping mechanism

narrow the gap with foreign advanced technology through four connections; Increasing the R & D strength of materials such as hydrogen fuel cell materials, special functional fluorocarbon materials, copper foil for high-energy batteries, and high-efficiency solar spectrum selective absorption coating, etc. the rod mechanism realizes the transmission of force, and its tightening direction is opposite to the external clamping type, which is mainly used to grasp thin-walled workpieces with inner holes. After the clamping mechanism supports the workpiece tightly, three fingers are usually installed to ensure that it can be positioned smoothly with the inner hole

Figure 5 structural diagram of internal supporting connecting rod lever clamping mechanism

5 The pneumatic system of the fixed rodless piston cylinder is as follows. The cylinder is a single acting cylinder, which is reversed by spring force and reversed by a two position three-way solenoid valve

Figure 6 pneumatic system of fixed rodless piston cylinder

a transition slider is installed at the radial position of the piston of rodless piston cylinder, and two hinged rods are hinged symmetrically at both ends of the slider. If an external force acts on the piston, the piston will move left and right, thus pushing the slider up and down. When the system is clamped, the hinge point B will make a circular motion around point a, and the up and down motion of the slider can increase a degree of freedom, and the swing of point C is used to replace the swing of the whole cylinder block

Figure 7 force increasing mechanism driven by fixed rodless piston cylinder

6 When the direction control valve of compressed air is in the left working state as shown in the figure, the left chamber of the pneumatic cylinder, that is, the rod free chamber, enters the compressed air, and the piston will move to the right under the action of air pressure to make the pressure angle of the hinge rod α Gradually reduce, with the help of the angle effect, Frederic Petit, the director of DSM's sustainable development, communication and brand building, said that the air pressure is amplified, and then the force is transmitted to the lever of the constant force increasing lever mechanism, and the force will be amplified again and become the force F holding the workpiece. When the direction control valve is in the right working state, compressed air enters the right chamber of the pneumatic cylinder, that is, the rod chamber, pushing the piston to move to the left, and the clamping mechanism loosens the workpiece

Fig. 8 internal clamping pneumatic manipulator of hinge 2 lever series force increasing mechanism

II. Air suction end clamping mechanism

air suction end clamping mechanism moves objects with the help of the suction formed by the negative pressure in the suction cup. It is mainly used to grasp glass, paper, steel and other objects with large shape, moderate thickness and poor rigidity. According to the negative pressure generation method, it can be divided into the following types:

1 Squeeze type suction cup

the air in the suction cup is squeezed out by the downward extrusion pressure, causing negative pressure inside the suction cup to form suction to attract objects. It is used to grab workpieces with small shape, thin thickness and light weight

Figure 9 structure diagram of extruded sucker

2 The air flow negative pressure suction cup

control valve injects the compressed air from the air pump into the nozzle. The flow of the compressed air will produce a high-speed jet, which will take away the air in the suction cup. In this way, a negative pressure is generated in the suction cup, and the suction formed by the negative pressure can suck the workpiece

Figure 10 structure diagram of air flow negative pressure suction cup

3 Vacuum pump exhaust suction cup

uses the electromagnetic control valve to connect the vacuum pump with the suction cup. When pumping, the air in the suction cup cavity is pumped away, forming a negative pressure and sucking objects. On the contrary, when the control valve connects the suction cup with the atmosphere, the suction cup loses suction and releases the workpiece

Figure 11 structure diagram of vacuum pump exhaust suction cup

III. hydraulic end clamping mechanism

1 The normally closed clamping mechanism

uses the strong preload of the spring to fix the drilling tool and release it hydraulically. When the clamping mechanism does not perform the grasping task, it is in the state of clamping the drilling tool. Its basic structure is that a group of pre compressed springs act on the force increasing mechanism such as the inclined plane or lever to make the slip seat move axially, drive the slip to move radially and clamp the drilling tool; The high-pressure oil enters the hydraulic cylinder formed by the slip seat and the shell, further compresses the spring, causes the slip seat and slip to move in reverse, and loosens the drilling tool

2. The normally open clamping mechanism

usually adopts the way of spring loosening and hydraulic clamping, and is in the state of loosening when the grasping task is not performed. The clamping mechanism generates the clamping force by the thrust of the hydraulic cylinder. The reduction of the oil pressure will lead to the reduction of the clamping force. Usually, a hydraulic lock with reliable performance should be set on the oil circuit to maintain the oil pressure

3. Hydraulic elastic clamping mechanism

loosening and clamping are achieved by hydraulic pressure. If the oil inlets of hydraulic cylinders on both sides are connected with high-pressure oil, the slips will collapse to the center with the piston movement, clamp the drilling tool, change the high-pressure oil inlet, and the slips will deviate from the center to loosen the drilling tool

4. Composite hydraulic clamping mechanism

this device has a main hydraulic cylinder and an auxiliary hydraulic cylinder. The side of the auxiliary hydraulic cylinder is connected with a group of disc springs. When the high-pressure oil enters the main hydraulic cylinder, it pushes the main hydraulic cylinder block to move, and transmits the force to the slip seat on the side of the auxiliary hydraulic cylinder through the top column. The disc springs are further compressed, and the slip seat moves; At the same time, the slip seat on the side of the main hydraulic cylinder moves under the action of spring force to loosen the drilling tool

IV. magnetic end clamping mechanism

is divided into electromagnetic chuck and permanent chuck. Electromagnetic chuck is used to connect and cut off the current in the coil, generate and eliminate magnetic force to attract and release ferromagnetic objects. The permanent magnet suction cup uses the magnetic force of the permanent magnetic steel to attract the ferromagnetic object. It changes the magnetic field line circuit in the suction cup by moving the magnetic isolation object, so as to achieve the purpose of attracting and releasing the object. But it is also a suction cup. The suction force of the permanent suction cup is not as large as that of the electromagnetic suction cup

article source: fixture man

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